Preheat your oven to 350° F. Next, spray a 13x9 (or any similar-sized baking dish) with non-stick spray. Set aside.
In a large mixing bowl, combine the pumpkin puree, evaporated milk, sugar, vanilla, eggs, pumpkin pie spice, and salt. Whisk to combine.
1 15 oz can pumpkin puree, ⅔ cup sugar, 5 oz evaporated milk, 3 eggs, 1 tsp vanilla extract, 2 tsp pumpkin pie spice, ½ tsp salt
Pour the pumpkin mixture into the prepared baking dish and spread evenly.
In a separate large bowl, combine the crushed Biscoff cookies, oats, brown sugar, baking powder, and baking soda to create the topping mixture. Stir them well to combine. Cut in the butter using either two forks or a dough cutter.
1 cup crushed Biscoff cookies, 1 cup oats, ⅓ cup brown sugar, ¼ tsp baking soda, ¼ tsp baking powder, ½ cup unsalted butter
The mixture should look crumbly.
Sprinkle the topping mixture over the pumpkin puree filling in an even layer.
Bake in the oven for approximately 35-45 minutes, or until the filling is bubbling and the topping is set and crispy. If you have a thermometer, check the internal temperature of the mixture; it should be 175° F degrees. A little wiggle in the center is okay as the filling will solidify once cooled.
Allow the crisp to rest and cool a bit before serving. Enjoy!